Living in North Texas in a pier and beam house, should I have a vapor barrier on the ground? Right now it is exposed dirt. If I need one and choose to lay plastic sheeting down, do I need to seal the separate sheets together or just overlap them by some amount?

I have to cut out the floor in a bathroom near the middle of the house this weekend so I thought this would be as good a time as any.

I found several posts about it that talk about the need for it (depending on where you live) but I can't find if I just overlap the different sheets or seal them together. I'm thinking seal because I read one response that indicated they were attached to the foundation and caulked.

Caulk and tape. Overlap the joints at least 1 foot and seal them. Another thing to do is to put ballast on them. I have seen the seam installed in a small ditch with some sand or even concrete in the hole to keep the seams from being disturbed.

Do it any way you want, your ahead of the game and doing the right thing. Try www.buildingscience.com for info that will make your head spin.

Installing a vapor barrier is fairly simple but you need to make sure you are doing it correctly or you'll be wasting your time. This website has a complete section on vapor barriers and how to install them:

A tip: check you local building code.
Strangely, some building codes do not allow crawl space encapsulation, and some only allow it under certain specifications.

An please beware!. Be really careful if you have combustion appliances in the crawl space!!! Those appliances need a consistent air flow to work and you don't want to depressurize the space around them. If you are not completely, 100% sure about what you are doing, please get a professional to do it.